I find people have the most fun doing unusual sports that they have adapted or invented to make the best of their environment or available equipment. These people pictured above seem to prefer sitting on large floating objects rather than comfortable lawn furniture.

Would anyone like to share their ideas for interesting and relaxing leisure activities or sports for the summer?

"Dead Man's Float"? That works for as long as you can hold your breath.
How 'bout exploring the province by town-hopping?

Board games. Cards. Origami. Hobbies. All possible to get neighbours to join in for an evening (or many evenings). These ideas can be almost non-cost (Travel and/or snacks=$), or totally off-the-wall expensive, if you enjoy gambling.
Or, we can sit in front of the boob tube, non thinking, non moving.
Any other delightful summer vacation ideas?

How about strolling through the neighbourhood at mealtime, smelling the cooked food from each home? Guess what it is. Best done quietly. This activity is only available to a non smoker! As an ex smoker, I know!